基于微通道板的电离室及其在同步辐射中的应用

Ionization chamber based on multichannel plate and its application on synchrotron radiation

在同步辐射装置中,气体电离室是定标光束线能量和评估能量分辨率的一个重要实验装置。为了摆脱电极探针式电离室的气体展宽对束线能量分辨率测定的限制,本文将微通道板(Microchannel Plate,MCP)应用于同步辐射光束线中的电离室,研制成功了具有高能量分辨率的电离吸收谱的探测系统。利用此系统测量标准气体在X射线入射时的电离吸收谱,通过分析测量所得谱线中吸收峰的展宽,可获得光束线的仪器展宽,本文以Ar的吸收谱为例给出了测量结果。

Background： The measurement of energy resolution is an essential task for commissioning a beamline in synchrotron radiation facility. The ionization chamber plays an important role in the evaluation of energy resolution. The conventional type based on electrode probe has the disadvantage of a low detection upper limit for energy resolution due to collision broadening on peak profiles by high working pressure （up to 1.33Pa）. Purpose： To improve the upper limit of resolution measurement, we aim to set up and deploy the ionization chamber based on multichannel plate （MCP） in China, including vacuum system, gas inlet system, detection system and data acquisition and processing system.Methods： Taking advantage of high amplification of a MCP detector, gas ionization absorption spectra can be measured under much low working pressure （1.33×10^4Pa）. By analyzing the width of absorption peak, the instrument broadening caused by a beam line can be obtained.Results： An ionization chamber based on MCP can achieve higher upper limit than those based on electrode probe in evaluating energy resolution. Conclusion： A MCP ionization chamber provides an important diagnosis for energy resolution in commissioning high performance beamlines.